Roland McGrath wrote:

This should be:

NOTE_KERNELCAP_BEGIN(1, 1)
NOTE_KERNELCAP(0, "nosegneg")
NOTE_KERNELCAP_END

i.e. 1->0 in the "bit" member.  (Note the ld.so.conf.d file must have the
matching bit number for ldconfig-based lookups to do the right thing.)
Or else:

NOTE_KERNELCAP_BEGIN(1, 2)
NOTE_KERNELCAP(0, "nosegneg")
NOTE_KERNELCAP_END

i.e. 1->2 in the "mask" member.  (The mask value should be 1<<bit.)
  

Thanks Roland.  I've never really understood this stuff, and I just
copied this cargo-cultishly.

I'm not quite sure what you're suggesting here though.  Do you mean one of:

NOTE_KERNELCAP_BEGIN(1, 1)
NOTE_KERNELCAP(0, "nosegneg")
NOTE_KERNELCAP_END

or

NOTE_KERNELCAP_BEGIN(1, 2)
NOTE_KERNELCAP(1, "nosegneg")
NOTE_KERNELCAP_END

is the correct thing to use?

Some pre-release glibc's (before 2.4) had a bug in the code that parses
this, and would crash parsing the correct note.  Using the wrong bit value
with nonmatching mask worked around this.  IIRC, no glibc release ever
included the buggy version of the code.  In nonbuggy glibc, the mismatched
value causes the "nosegneg" to be omitted from the directory search (under
LD_LIBRARY_PATH and default directories), though ldconfig-based lookups
will work (the most common case).
  

Are you saying that one of the corrected forms might cause old glibcs to
crash, or just ignore nosegneg?

    J